Q vs K

[Eileen Si 1G]

This may be an obvious question, but what is the difference between Q (reaction quotient) and K (equilibrium constant)?

[Alicia Lin 2F]

Q is calculated the same as K. However, Q is not necessarily at equilibrium while K is.

[Giselle Littleton 1F]

The reaction quotient Q describes the ratio of products to reactants when the reaction in a non-equilibrium state. K describes the same thing only when the reaction is at equilibrium.

[Vicki Liu 2L]

Another important thing to note is that by comparing the values of Q and K, you can predict how the reaction will proceed. If Q=K, the reaction has reached equilibrium. If Q<K, the reaction will form more products and if Q>K, more reactants.

[AKatukota]

Q refers to the direction that the reaction will proceed in. You use Q in comparison to K. For example, if Q<K, then the reaction favors reactant production. If Q>K then it favors products. If Q=K, then the reaction is at equilibrium.

[BCaballero_4F]

K is used for when it is at equilibrium

[Rida Ismail 2E]

K is strictly for when the equation is at equilibrium. If it is not at equilibrium then the constant Q is used but they are calculated the same way. Maybe comparisons can then be made about K through the values of Q surrounding it.

[Dina 2k]

I'm not sure if this has been asked, but how did you guys come to the conclusion for the answer to 5G.11a. I understand that to find Q, its the same process as finding K, but the solution manual for 11a doesn't show that.

[sarahsalama2E]

Yes, as mentioned above Q is not the same as K. Q is the reaction quotient and K is when the chemical reaction is at equilibrium ONLY. If q is less than K, then the reaction will proceed to the right and if q is greater than K then the reaction will proceed to the left.

[Minh Ngo 4G]

K is the value of molarity of P/R at equilibrium while Q is not at equilibrium (usually at initial condition). They are, however, calculated the same. Molarity or partial pressure ratio of P/R

[Emily Vainberg 1D]

Q and K are both calculated the same: Concentration of products/ concentration of reactants

The only difference is that K is used when the reaction is at equilibrium, which is a specific point. Q can be used throughout the reaction before equilibrium is reached. Comparing the two lets you predict which way the reaction will continue.

[Kavya Immadisetty 2B]

Although Q and K are calculated the same way, the difference is the state of the reaction at the time when this is calculated: Q can be any specific point of time while K must be when the reaction is at equilibrium.

[Nicholas_Gladkov_2J]

This may be an obvious question, but what is the difference between Q (reaction quotient) and K (equilibrium constant)?

k is a constant that is temperature dependent (one per temperature) that is solved when the reaction reached equilibrium. Q is when the reaction has not reached equilibrium, but is solved exactly like k.

[Anushka Chauhan2B]

The value of K is determined when the reaction is at equilibrium, while the value of Q is when the reaction is not at equilibrium.